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MQTT QoS & Flag
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MQTT QoS & Flag

by niccolorgu on Sun Jan 17, 2021 7:49 am

I have set up a raspberry pi and am connecting to AdaFruit feeds using Adafruit IO MQTT API.

I have the following code working and would like to know how to modify it to set a QoS or retain flag;

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# Example of using the MQTT client class to subscribe to and publish feed values.
# Modified from examples by
# Author: Tony DiCola
# https://github.com/adafruit/Adafruit_IO_Python/tree/master/examples/mqtt

# Import standard python modules.
import random
import sys
import time

# Import Adafruit IO MQTT client.
from Adafruit_IO import MQTTClient

# Set to your Adafruit IO key.
# Remember, your key is a secret,
# so make sure not to publish it when you publish this code!
ADAFRUIT_IO_KEY = 'Activity Key'

# Set to your Adafruit IO username.
# (go to https://accounts.adafruit.com to find your username)
ADAFRUIT_IO_USERNAME = 'username'


# Define callback functions which will be called when certain events happen.
def connected(client):
    # Connected function will be called when the client is connected to Adafruit IO.
    # This is a good place to subscribe to feed changes.  The client parameter
    # passed to this function is the Adafruit IO MQTT client so you can make
    # calls against it easily.
    print('Connected to Adafruit IO!  Listening for DemoFeed changes...')
    # Subscribe to changes on a feed named DemoFeed.
    client.subscribe('DemoFeed')

def disconnected(client):
    # Disconnected function will be called when the client disconnects.
    print('Disconnected from Adafruit IO!')
    sys.exit(1)

def message(client, feed_id, payload):
    # Message function will be called when a subscribed feed has a new value.
    # The feed_id parameter identifies the feed, and the payload parameter has
    # the new value.
    print('Feed {0} received new value: {1}'.format(feed_id, payload))

# Create an MQTT client instance.
client = MQTTClient(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)

# Setup the callback functions defined above.
client.on_connect    = connected
client.on_disconnect = disconnected
client.on_message    = message

# Connect to the Adafruit IO server.
client.connect()

# Now the program needs to use a client loop function to ensure messages are
# sent and received.  There are a few options for driving the message loop,
# depending on what your program needs to do.

# This is why the python modules random, sys, time have been imported
# The first option is to run a thread in the background so you can continue
# doing things in your program.
client.loop_background()
# Now send new values every 10 seconds.
print('Publishing a new message every 10 seconds (press Ctrl-C to quit)...')
try:
  while True:
    value = random.randint(0, 100)
    print('Publishing {0} to DemoFeed.'.format(value))
    client.publish('DemoFeed', value)
    time.sleep(10)
# If you do not have a feed called DemoFeed, one will be created with the first message.
except KeyboardInterrupt: # detect ctrl+c and handel it
  client.disconnect()

niccolorgu
 
Posts: 4
Joined: Wed Jan 13, 2021 5:37 pm

Re: MQTT QoS & Flag

by brubell on Wed Jan 20, 2021 11:34 am

Adafruit IO does not support /retain functionality, but it supports a similar /get functionality: https://io.adafruit.com/api/docs/mqtt.h ... -get-topic


For QoS, add a `qos` kwarg to the client.subscribe call:
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client.subscribe('DemoFeed', qos=1)

brubell
 
Posts: 1344
Joined: Fri Jul 17, 2015 10:33 pm

Re: MQTT QoS & Flag

by niccolorgu on Wed Feb 03, 2021 11:20 am

Thank you

niccolorgu
 
Posts: 4
Joined: Wed Jan 13, 2021 5:37 pm

Please be positive and constructive with your questions and comments.